Vibrations at 80+

[RAU03MACH]

think of it as your spine

 

[RAU03MACH]

it's reinforced internally

 

[dsrtjeeper]

keep in mind the ford racing aluminum shaft
is spiraled inside no flex

It still flexes at it's critical speed. It starts to whip like a jump rope. I used to have a video of mine doing so. I placed a camera under my chassis to record it.

Also, the driveshaft is not spiraled. The cardboard tube inside is. It's used for dampening.

https://www.dieselplace.com/attachments/dscn0329-jpg.77046/

 

[OldZeuski]

It still flexes at its critical speed. It starts to whip like a jump rope. I used to have a video of mine doing so. I placed a camera under my chassis to record it.

I just don’t understand how everyone seems to say when they switched to an aluminum shaft it fixed their vibration issues. I can’t be the only person with a ford performance aluminum shaft that gets the car over 80 mph. And I’m not sure I believe 4200 rpm is the critical speed of an aluminum tube.

The equation for critical speed is easy to solve. I seriously doubt the critical speed of this shaft is anywhere below 7500 rpm.

 

[RAU03MACH]

The one i have is
But mine was built in the 90s shit now not worth a shit
Better quality

 

[dsrtjeeper]

Not everyone. Look into the new Mustang crowd. One driveshaft manufacturer discontinued their aluminum shafts for them due to so many issues with vibrations. The ideal aluminum shaft for our cars would be 4" in diameter and thicker than the Ford Racing shaft. Unfortunately, we can't fit a 4" shaft under our cars.

I tried the calculations for critical speed. You have to know the thickness of the aluminum to do so. I'm baffled by the numbers too. Carbon fiber shafts aren't just for weight savings. They often fix vibrations.

Something to consider is not all driveshaft balancing machines are alike. If your shop can only balance the shaft with the yokes removed, they're worthless. It's important that the shop has the capability to balance with yoke installed and at high speeds. Many shops balance shafts at under 1000rpm.

 

[dsrtjeeper]

The one i have is
But mine was built in the 90s shit now not worth a shit
Better quality

This has been stated many, many times. The Ford shafts went to crap. I've had two new ones with bent tubing.
Mark Williams straightens the tubing before building a shaft. Their shafts don't need weights attached. They are a piece of art.
I'm currently switching to the new LMR shaft that's high speed balanced and has no weights.

 

[RAU03MACH]

I have had mine since I bought my mustang in 95
And that shaft holds up pretty good
And im not a light foot by all means

 

[RAU03MACH]

Hang tight i will put a little more horses on that shaft
I will be starting the 351 build soon
Many of the mustang guys run these shafts with no problems
I would be looking at the whole drive line for vibrations
Including all control arm bushings
Clutch flywheel

 

[RAU03MACH]

Down to a simple tire balance